Laura Haeckl Brannin, social activist, was the daughter of Joseph and Elizabeth Haeckl of Cincinnati, Ohio, where she was born on February 8, 1888. Her paternal grandfather had fled the draft in the German states by immigrating to America; her father was a skilled cabinetmaker, active member of the carpenter's union, and a religious skeptic. Laura and her three siblings were able to complete high school, but extensive college courses were beyond their financial reach. Laura graduated from Hughes High School in Cincinnati and took a few business-college courses and night courses at the University of Cincinnati. She encountered Herbert Bigelow's People's Church in Cincinnati and immediately accepted its Unitarian creed, free-wheeling discussion groups, and interracial membership. She was an active participant in the Church's People's Power League, a political organization concerned with a variety of municipal issues. It was through the church that she met her future husband, Carl P. Brannin, a native Texan. Brannin had gone to Cincinnati to be the editor of the People's Press, the newspaper published by the People's Church. When Brannin quit the paper in 1917, Laura succeeded him as editor. In March of 1918 they were married.
Laura often worked at clerical and social work jobs and generally served as Carl's alter ego. She traveled abroad with him, moved to Dallas in 1933 with him, wrote her own letters to the editors of the Dallas newspapers, and actively participated in Socialist affairs in Texas in the mid-1930s. Laura organized a series of lectures in Dallas for the League for Industrial Democracy. She joined Carl in the Unitarian Church of Dallas in 1947, and in the civil-rights battles of the 1950s and 1960s in the city. The Brannins were feted by the state's liberal community in 1963 for their "selfless" dedication to progressive causes. In one of Laura's last letters, in the Dallas Morning News of January 28, 1965, she wrote, "The sensible thing to do is to admit that China exists, then to be ready to talk to her and trade with her. Trade–it is a magic word–one of the most powerful deterrents to war." Just prior to her death, she and her husband established the Laura and Carl Brannin Collection of Religion in Social Action at the Bridwell Library of the Perkins School of Theology, Southern Methodist University. Laura Brannin died of cancer of the liver on August 11, 1965. In May of 1966 the Catholic Interracial Group awarded the Brannins the Father John LaFarge Award for the couple's civil-rights work. The Brannins had one adopted son, Robert.